Conventional household clothing washers use anywhere from about 60 liters to about 190 liters of water to wash a typical load of clothing articles. The spent water and cleaning agents are then dumped into sewage. Furthermore, the water is frequently heated to improve wash effectiveness and usually requires a large amount of energy to be put into the articles as heat in order to vaporize the retained water and dry the articles. The combination of high water usage, high-energy usage and disposal of cleaning additives in the detergent can put a large strain on the environment.
Conventional perchloroethylene (PERC) professional dry cleaning solvent has been shown to be hazardous to human health as well as to the environment. Use of a cyclic siloxane composition as a replacement for PERC is described in Kasprzak, U.S. Pat. No. 4,685,930 and Dullien et al., U.S. Pat. No. 6,063,135. The use of a siloxane solvent in laundering has been shown to result in reduced wrinkling, superior article care, and better finish than water washing. Furthermore, the siloxane solvent has a lower heat of vaporization than water. Compared to water, the siloxane solvent can be more easily dried out of the article. If a washing machine contained a solvent based cleaning cycle, the solvent cycle could replace some or all of the washing currently being done in water, which would result in a significant reduction in energy and water use.
There are currently commercial dry cleaning machines, which use a cyclic siloxane dry cleaning process, but these machines present several barriers to in-home use. Known commercial dry cleaning machines are generally much larger than typical home washing machines, and would not fit within typical washrooms. These commercial dry cleaning machines typically require high voltage power (>250V) and often require separate steam systems, compressed air systems, and chilling systems to be attached externally. The solvent amount generally stored in the commercial dry cleaning machines is usually more than about 190 liters, even for the smallest capacity commercial machines. The typical dry cleaning facility has both solvent cleaning and water cleaning machines on the premises and uses each machine for their separate functions. Known commercial dry cleaning machines are typically designed to be operated by a skilled employee and do not contain appropriate safety systems for either in-home locations or for general use. In many states, the use of commercial dry cleaning machines by the general public is forbidden.
U.S. patent application Ser. No. 10/127,001, titled “Apparatus and Method for Article Cleaning”, filed on Apr. 22, 2002, commonly assigned to the same assignee of the present invention, represents one innovative implementation of an appliance that provides solvent, or water-based cleaning (or combination thereof). As set forth in the foregoing patent application, this appliance may be advantageously accommodated either in an in-home or in a coin-operable laundry setting. That is, an appliance that may be used not just for commercial dry cleaning applications, but also having the appropriate small size, cost, and user-interface considerations for a home-based laundry system.
Presently, the standard technique of solvent reclamation in a commercial dry cleaning process is distillation of the PERC solvent. Impurities may be concentrated in the distillate bottoms, and disposed of. Unfortunately, significant exposure to the solvent as well as the impurities is possible.
Another technique of solvent reclamation is through an adsorption system. Although known adsorption systems may provide some cleaning action to the solvent, this technique generally needs to be used in conjunction with a distillation set-up in order to provide long term use of the recycled solvent. In the industrial setting that this technique is used, the adsorption system typically requires use of large canisters that are cumbersome and may lead to user exposure to the solvent and contaminants.
Water removal in industrial dry cleaning equipment is usually minimal, and many dry cleaning machines are equipped with a decanter for this purpose. These known decanters are typically operated in a continuous fashion. It is believed that continuous operation of decanting equipment would not be suitable for home use.
In view of the foregoing considerations, it would be desirable to provide a system and process that is economically affordable for quickly and reliably purifying and reclaiming siloxane cleaning solvent for reuse, as may be utilized in a solvent cleaning appliance, such as described in U.S. patent application Ser. No. 10/127,001. It is further desirable that such a system be configurable to meet the unique considerations of an in-home appliance as well as those of commercial scale units, such as coin-operable laundry machines.